Beijing police officer Zhang Hui Ling, who patrols Haidian District's Shuangyushu neighborhood in Beijing, has a job to do. Every day, he has to go out in the street with his cohort of security guards who speak a bewildering array of accents from all over China, and track down and arrest thieves, hucksters, and con artists. And he's good at it; after more than 10 years on the force, Zhang Hui Ling has an uncanny ability to sniff out criminals from the throngs of people passing through his district. He needs those skills in Shuangyushu, a migrant neighborhood where criminals congregate. Like the car thief who steal BMW's and Mercedes with interface gadgets he buys on the Internet, or the family gang who crash cars into passing automobiles and demand settlement on the spot, or the currency counterfeiters, con artists who dress as monks to defraud religious old women in crisis, or the former thief who was injured during his last arrest and now hounds his unemployed younger brother for cash, or the retired master thief who is looking for a way to reclaim his former glory. These thieves, con artists, and criminals, and the bottomless pain and bitterness buried in their hearts, are the underworld in this society. And these people, criminals of every sort, are the type of people Zhang Hui Ling has to deal with every day. There's no outlet for the humiliation and misery he endures as part of it. His job is to face it and deal with it, to stop crimes from happening. But he can't help feeling like it's partly his fault that he's failing, somehow, because the crime and misery doesn't stop. In the depths of his spirit, the positive and negative forces in his life grapple, every day, every crime, every arrest, every bit of mercy and understanding renewing the endless battle for his soul.